Extension cord questions

[pellegrino]

So I'm in the market for a new extension cord and I wanted to run a few things by folks to see if some of my ideas are even feasible.

Primarily this cord needs to take power from the outlet on my back porch to my garage, a distance of about 75 feet. (I would run a separate circuit to the garage if I could, but it's impossible). For this I figure a 10 gauge extension cord will be sufficient.

I would like for this cord to also double as a means to get power from a generator to the electrical panel so that in the case of an emergency we could run the thermostat for the heater (gas) and or the refrigerator/freezer from the panel.

I am comfortable making a custom cord but I don't know exactly what I need other than 10/4 wire. I am also open to other options for powering the thermostat. I've heard of using car batteries as a backup, but I've no idea how to go about that.

[pellegrino]

The receptacle on your back porch is only connected to one 120V leg of your home's power. That's fine for running things in your garage on your extension cord (size your wire depending on the load you expect to pull and given the recommended 5% maximum voltage drop). However, any power you push the other way through a generator will only feed half of your home's circuits and provide only 120V to any 240V circuits that you have. I wouldn't recommend you do that.

Where is your distribution panel located?

cheers.

Perhaps I didn't explain the generator connection well. I don't anticipate powering the whole house, or even half of it, just a few essential appliances (refrigerator/freezer) and the thermostat for a gas furnace (obviously only in cold weather), which is low voltage anyways. I also never planned on using the same receptacle to power the grid, rather I was planning on installing a separate receptacle (likely a 30 amp 4 prong twist plug) connected to a transfer switch which would then be wired to the panel. Is that unrealistic?

The panel is in the basement about 2 or 3 feet below the receptacle I'm using to get power the garage. Would it be possible to use the same receptacle to both get power to the garage and then reverse power the house?

[pellegrino]

OK, I'm getting a clearer picture (I think).

If I understand you correctly, there currently exists an outdoor receptacle on your exterior wall that is immediately above your panel (which is located in your basement). The outdoor receptacle is a normal 120V 3-wire plug. To power your garage, you currently plug an extension cord into this receptacle and then string the cord across the yard and into the garage. Is that correct?

This is correct

I'm just curious, is the surface between your home and your garage impermeable?

If it isn't, have you considered digging a trench and installing some conduit from your house to the garage?

I wish I could. Unfortunately there is a 20' wide cement alley between my the end of my backyard and my garage. The HOA won't let me dig that up just to get power. The only other option is to have the electric company install a service box and pay a separate bill for it. Not interested.

To convert your current outdoor receptacle into a 30 amp 4-wire plug (L14-30), then you are going to have to run another wire up to your existing 120V 3-wire receptacle (from the other 120V leg) in order to convert it into an L14-30 receptacle. So you may as well run a separate 10/3 Romex wire and have both the existing 120V (to the garage) receptacle and the 240V (to the generator) receptacle installed side by side. The new Romex wire you snake up to the new receptacle will connect into your panel on it's own circuit, or into a transfer switch if that's what you want to do.

Personally, I would just direct wire your generator receptacle right into your panel. Then keep the breaker in an "OFF" position until you need it. When your power goes out, transfer the power from the grid to your generator by performing the following steps: 1) switch off the main 200 amp service breakers in your panel, 2) turn your generator breaker on, 3) turn off any individual house breakers that you don't want the generator to run, 4) connect your generator to the receptacle, and then 5) fire up your generator.

When the power is restored in the area, reverse the process: 1) turn off the generator, 2) disconnect your generator from the receptacle, 3) turn off the breaker to the generator receptacle, 4) turn on all of the other house circuit breakers, and then finally 5) turn your main 200 amp service breakers.

Basically, you become the transfer switch. This is what I do... for the 1 or 2 times a year the power is off longer than a couple of hours (in my area), I figure it's not worth the expense/time to buy/install a transfer switch. YMMV.

If I'm totally misunderstanding your situation and not giving you any helpful advice, then it just PM me your phone number and I'll call you. It was just the year before last that I installed a L14-30 receptacle in my garage, wired it into my home panel, and built my own generator cord (for which I used 8-gauge wire because of length).

cheers.

More or less that is what I want to do, but not immediately. We don't have a generator yet, it's in the budget before next winter (our main concern is losing power in a winter storm and not being able to heat the house because the thermostat doesn't work). Right now I want to buy or make a cord that will be hopefully able to do double duty in both getting power to the garage and (eventually) getting power to the house from a generator if needed. I wasn't sure if that was possible but from the information you've given me it seems it may be.

Here's an ideal scenario. Let me know if this sounds feasible. Replace the 120 v receptacle with an inlet box like the one you linked above. Wire the inlet box directly to a circuit on the panel (or possibly to a transfer switch, have to check the code to see if it's mandatory here) on its own 30 amp circuit. Keep it switched off normally and then when I need power in the garage, flip it on, plug in the extension cord and send power to the garage. When the power goes out, I follow the procedure you outlined above. I realize that it would leave me with a male plug in the garage, but it wouldn't be hard to make a small cord with female plugs on both ends. I could even make them twisting so as to guarantee a secure connection.

What do you think?

[FN Phat]

Here is the how-to that Space Ghost had posted about generators. Very helpful and, as always, a great write-up.

http://www.cougaruteforum.com/showpo...42&postcount=7

I hope that helps. It seems that you and Space Ghost have this situation under control!

[UtahDan]

[pellegrino]

What follows may be a bit disorganized, but here is what I think...

The first thing I'd do is get a feel for how I could convince you not to convert your existing 120V exterior receptacle into a 240V one because I think it would be more useful to have both.

If the existing 120V receptacle is mounted on the surface of your exterior wall, then I'd probably lean toward installing another box right next to it and having two receptacles side-by-side: one 120V, and one 240V.

If your existing outdoor receptacle is installed "inside" your wall cavity and flush with your exterior wall, then I would want to have the 240V plug also installed in like manner. However, I don't know what kind of material you have on the outside of your house. Is it siding? brick? Some exterior treatments would make installing a second receptacle quite problematic. So, if it is difficult to install a second receptacle on your exterior wall, then this may explain your reluctance to do so.

If you absolutely must keep just one box, then you will have to rewire the existing box. Which means you'll have to isolate it from whatever circuit it is currently on. If the receptacle is the only thing on the circuit, then it will be somewhat trivial. However, if it isn't the only device on the circuit (which is likely), then you'll have to remove it from the existing circuit, splice the wires together to maintain the integrity of the circuit, and then pull up some new 10/3 wire. This is the main reason why I suggested you just install a new 240V receptacle by your current 120V one. You're likely going to have to pull new wire anyway. Might as well make it nice and clean (IMHO).


So there are two scenarios now, which I'll address:

1. You install two receptacles. In this case, you can just use an off-the-shelf 75' 3-prong extension cord to power your garage; and an off-the-shelf (shorter) generator cord to connect your generator to the house. When you need the generator, you would wheel it out of storage, set it up by your new receptacle, connect it, and fire it up. I don't like the idea of building a 75'-long generator cord. It's expensive and the power loss over that length might be problematic. Also, in this situation, installing a transfer switch is an option... since the generator circuit is separate from your garage circuit.
   
2. You convert the existing receptacle from 120V to 240V. In this case, you would build (or buy) a long generator cord with standard male/female connections. The female end would go into the new 240V receptacle at the house, and the male end would either 1) go into the generator when needed, or 2) plug into a female twist-lock receptacle that you install in your garage to power your garage wiring. In this situation, you cannot have a transfer switch since you would need the circuit to provide unobstructed power to the garage in "normal" (non-generator) mode.

In either situation, I would wire your garage up such that all you need to do is plug in one of the aforementioned extension cords into a single plug in your garage that would "light up" the whole thing. Basically, you would install a (weatherproof) receptacle on the exterior wall (of your garage) that would receive the male end of the extension cord. From this outlet, run wire around your garage to power other receptacles and to power any overhead lighting. If you decide to use a 240V generator cord to power your garage, then take one of the 120V leads (e.g. the black wire) and power any receptacles you install around the garage, and take the other 120V lead (e.g. the red one) and run it up to a switch to power your overhead lighting. If the interior walls of your garage are not finished (bare studs), then wiring your garage will be trivial. Also... wiring your garage in his manner also eliminates the need for you to have a male outlet in your garage... you'd be using standard male/female-ended cords.

With regard to the transfer switch and checking code to see if it is mandatory... I wouldn't bother. But then, that's how I roll.

It sounds like a fun project, I wish I lived nearby (or do I?)... I'd definitely be willing to contribute labor and expertise.

cheers.

Good write up. I'll likely go with #1. In looking at the receptacle that is there and seeing what else is on that circuit it makes sense to leave it there and install a new 240V receptacle when the time comes. I can put it next to the 120V or somewhere in the area. The current receptacle is flush to our brick exterior, and I don't feel like cutting into the brick to make it match, but that's ok with me. I do plan on eventually wiring the garage and installing a twist lock receptacle for the extension cord. It's cement block and I don't want to bother drilling through it, I'll just put it inside the door. This will have to wait though. I can spend money on wiring the garage or put that money toward some of the projects I want to make in the garage. I don't mind making do for a while and then when it does come time it'll be easier to convince the wife because I'll have a body of work to back me up.

Thanks for the discussion. It's always good to be able to throw ideas around and see what the best option is.

[pellegrino]

Not bad, do you have that in your office? I hate to think what kind of light it would put off. It'd send off a funky disco vibe, or make everything look like cheap makeup.

[clackamascoug]

Clue #22 on why I'm a social outcast.

I can't look at the brown extension cords without remembering my childhood. My mom would loop it in a cat of nine tails fashion, and whip me with it, leaving bleeding welts on my legs. After I got to 13 and was bigger than her, I let her know that beating me with extension cords was no longer an option.

True Story,

-Clack